Lay-in type suspended ceiling and panel therefor



April 7, 1970 i o. w. AKERSON 3,504,462

LAY-IN TYPE SUSPENDED CEILING AND PANEL THEREFOR Filed Sept. 30,1968

INVENTOR. 0A /0 W AKERSON United States Patent US. Cl. 52145 12 Claims ABSTRACT OF THE DISCLOSURE In a lay-in type suspended ceiling, the acoustical panels are comprised of boards of mineral fiber bonded together with an hydrophilic binder, which boards are faced with a perforated metal foil facing and backed with a moisture impermeable membrane, preferably also a metal foil.

The foil facing prevents excessive sagging and the foil backing overcomes warping at the panel corners.

This application is a continuation-in-part of my copending application Ser. No. 687,583 filed in the United States Patent Ofiice on Dec. 4, 1967.

This invention relates to a lay-in ceiling as distinguished from a tile ceiling.

One object of this invention is to provide an improvement in the lay-in panels faced with a metal foil as disclosed in my earlier application.

Another object of this invention is to provide a washable, and repeatedly washable, facing on lay-in panels, which facing also provides a damage resistant surface.

Still another object of this invention is to overcome the warping of the foil faced panels of my earlier invention when they are exposed to extremely severe variations in humidity.

These and other objects will be understood by those skilled in the art from the accompanying specification and drawings in which:

FIG. 1 is a prospective view from beneath of a lay-in ceiling, and

FIG. 2 is an enlarged view of one edge of one of the panels from FIG. 1.

Of the many types of ceilings currently being installed, particularly in commercial construction, two of the most common are referred to in the industry as lay-in systems and tile systems. As understood in the industry, and as used herein, the two systems may be distinguished largely by difference in size.

Commonly, lay-in ceilings incorporate panels or boards of a dimension of at least 2' x 2. In contrast, tile ceilings utilize tiles of generally 1 x 1', although sometimes such tiles are provided in 1' x 2 sizes.

Another distinguishing feature between the lay-in systems and tile ceilings is that the large panels of the lay-in ceilings are supported by resting upon a grid made up of runners and cross members which are of an inverted T shape in cross section. Thus the lay-in panels merely rest on the suspension system, which is generally referred to as an exposed system. In contrast, tiles are mounted in a number of ways which do not normally expose the suspension system. Tiles may be nailed, screwed, or adhered to a completed ceiling, or they may be mounted in a suspension system specifically designed to hide the suspension system in kerfs cut into edges of the tiles.

Lay-in panels are merely square cut on their edges and extend in size, as indicated above, from 2' x 2' in dimension on up, with 2' x 4 being the most common dimension. Larger sizes are sometimes provided, but normally not in excess of 2' in width. Thus, panels 2 x 5' and -2' x 6' are known.

3,504,462 Patented Apr. 7, 1970 The lay-in system generally enjoys a greater volume of sales in the industry, due largely to the lesser cost per square foot of producing a square cut board as opposed to one requiring additional working of the edges such as is required with tiles. Another reason for the general economy of lay-in systems is the ease of installation and the minimum amount of suspension system needed.

For certain applications, however, lay-in panels were not acceptable prior to the invention disclosed in my earlier application. Generally, in areas of excessive humidity, such as restaurant kitchens, bathrooms, and swimming pool areas, a highly washable surface is required. For these types of applications, recourse has been had to tile systems in which the tiles are faced with a metal foil, generally extending at least part Way up the edges of the tiles. Such metal foils serve to provide a hard and washable surface for such applications as mentioned above Where repeated washing or sanitizing, such as in hospitals, is required.

As pointed out in my earlier application, previous to my invention disclosed therein, lay-in panels had not been provided with metal foil facings. It is not known exactly why such products had not been available; however, it is believed due to the fact that large panels tend to sag or pillow in the center, thus giving an undulating and unpleasing appearance to the ceiling.

Because of fire code requirements, most all lay-in panels are made from mineral fibers bound together with a suitable binder. The common binder is starch, which is hydrophilic. Starch, of course, is used primarily for economy. When suchpanels are mounted in high humidity areas, being supported only at their edges, the humidity tends to weaken the starch bond, thus permitting the board or panel to sag noticeably toward the center. Any additional weight added to the panel tends to aggravate this difficulty.

Even without added weight, such mineral fiber panels bound with hydrophilic binders have required additional treatment such as a resin coating on the back side in order to bring the sag characteristics within acceptable limits. Under such circumstances it was not to be expected that the added weight of metal foil facings could be tolerated, since metal foils are not in themselves selfsupporting.

As disclosed in my earlier application, I discovered that foil faced mineral fiber boards with an hydrophilic binder could be produced which do not sag beyond acceptable limits. I have found, however, that panels so produced tend to warp in a different manner if exposed to extreme high humidity and then are subjected to more normal humidity, all as more fully described hereinafter.

In the drawings, FIG. 1 shows a suspension system for a lay-in system, including lay-in panels 10, longitudinal runners 12, and cross members 14.

The cross section of a runner 12 is shown in FIG. 1 as comprising a vertical web 16 and horizontally disposed flanges 18 and 20. The cross section of the cross members 14 is not shown but is substantially identical to the cross section of the runners 12.

The runners 12 are supported from a permanent superstructure, such as a concrete deck (not shown), by means of Wires 22 fastened to such a deck at one end and at the other end to the web 16 of the runners 12.

It will be seen that the panels 10 merely rest upon the horizontal flanges 18 and 20 of the suspension system runners 12 and cross members 14. As such, the suspension system comprised of the runners 12 and the cross members 14 is exposed, at least to the extent of showing one face of the flanges 18 and 20. This arrangement permits the panels 10 to be removed by pushing upwardly, thus permitting access to pipes, duct work, electrical conduits, and the like hidden above the suspension system ceiling and beneath the deck above. This ease of access is another of the reasons for the general popularity of this type of ceiling.

The panels 10 of the instant invention are also shown in FIG. 2, wherein they areshown to.comprise a body portion 24 and a metal foil facing member 26.

The body portion 24 is comprised of felted synthetic mineral fi'bers bound together by a suitable economic binder such as thehydrophilic binder starch. The facing 26 is preferably of aluminum foil but may be any of a number of other metal foils, such as tin, brass, stainless steel, and the like. In the preferred embodiment, the foil 26 is an aluminum foilof 4 mils in thickness. Although thicknesses as thin as 2 mils may be used, the heavier thicknesses are more damage resistant in hard use applications. Thicknesses greater than 4 mils may, of course, be used; however, such are avoided for reasons of economics.

The metal foil facing 26 is adhered throughout substantially its entire extent by means of an adhesivevto the front surface of the body 24. It has been found that in the absence of such substantially complete adhesion, the panel will not function adequately when in place due to sagging.

The panel 10 is also provided with relatively minute acoustical openings 28 punched through the metal foil 26 and into the body board 24. These acoustical openings are generally of a size of between and in diameter. There are a myriad of such minute perforations in the front surface of the panel 10. These acoustical openings provide access into the sound absorptive body board 24 for acoustical energy-sound-impinging upon the face of the metal foil 26. The metal foil itself is, of course, not acoustically absorptive and the body board 24, in the absence of the openings 28, would not be particularly sound absorptive either. The openings 28 permit the sound to enter well into the body board 24, where the sound is absorbed in known fashion in the interstices of the fibers. Generally the fibers arrange themselves in layers parallel to the plane of the panel and, consequently, some means of introducing the sound energy into the body of the board is required. However, these openings 28 also permit access into the interior of the board for the humidity of the atmosphere which deleteriously affects the hydrophilic binder.

In one accepted test for sagging, a ceiling of lay-in panels is supported in an enclosed tent, or room, where the humidity and temperature may be controlled. In such a test, the maximum permissible limit along the 4 length of a panel is 0.25" downward sagging. As disclosed in my earlier application, applicant has found, contrary to expectations, that with a metal foil facing such large panels will sag only between .08" and .10".

I have found, however, that when the panels of my earlier invention are exposed to extremely high humidity and then, are subsequently exposed to lesser or more normal humidity, while they do not sag excessively, they do Warp in an unusual manner. Under such circumstances the board surface is not really very much below the level of the suspension system and falls well within the usually considered acceptable limit of 0.25" downward sagging mentioned above; however, the four corners of the board raiseup fromMz. to /2." above the horizontal flanges 'of the suspension system. This creates a warped effect at the corners which is aesthetically disadvantageous. I have found that by adhering a moisture impervious membrane over the opposite or back surface of =the board, this corner warp problem is overcome completely. Indeed, I-have foundthat such a membrane, particularly when a metal foil is used, is so effective that it not only prevents the above mentioned corner warping but also eliminates sag to such an extent that the normal resin coating on the back side of the board may be eliminated. I v p In the drawings, the moisture impermeable membrane is shown as comprising an aluminum foil 30 of a thickness of about .002" adhered over substantially the entire back surface of the board 10. While other moisture impermeable membrances such 'as sheet plastic films may be used, and thicker or thinner metal foils such as steel, tin, brass, and the like may also be-used, aluminum foil of about .002. in thickness is preferred to such other metal foils and-to plastic 'films' for reasons of ease of handling, economy, weight, durability, fire resistance, and the like.

In my copending application, Ser. 'No. 763,904, filed simultaneously with this application on Sept. 30, 1968, I disclose another invention by which such corner warp may be eliminated. In thatapplication, Ser. No. 763,904, I disclose the use of an embossed foil of less than .004 in thickness as being effective to eliminate corner warp. Where it is desired to have a smooth surface for aesthetic or other reasons or where more durable films of a thickness of .004" or greater are desired, the use of the back surface membrane of this invention is particularly useful. This is particularly so since the back membrane and the front foil need not be of the same thickness or have the same, or even similar, tensilestrengths or expansion and contraction characteristics. Thus, for example, the front face foil may be twice as thick as the back foil, or even more. Indeed, as indicated above, a front foil thickness of .004" and a back foil thickness of .002" is preferred. Additionally, the front foil must be pierced with openings to permit access to the interior of the board for sound energy impinging upon the board. Such'construction is dictated by the acoustical absorption requirements of such panels. The back surface of the panel, however, must not be so pierced or the sound absorption or sound attenuation qualities of the board, or both, will be deleteriously affected. The punching of only the front face of the panel, including the front foil facing, while the back face of both the board and the back foil are left intact necessarily makes the panel asymmetrical as to its stresses both in compression and tension. Also, because the acoustical openings provide access to the board only from the front, the board would be expected to be asymmetrical from front to back with respect to its rate of moisture absorption and rate of drying (-when the moisture is given up upon lowering of the environmental humidity). Such asymmetry in the panel would be expected to produce either sag or corner warp or both in the panel upon exposure to wide variations in environmental humidity. Surprisingly, however, such has not proved to be the case.

Table I shows the sag and corner warp test results for two Examples I and II. The examples were each comof 2' x 2', 2' x 4, and larger for the panels 10, it is to be understood that in the industry these dimensions refer to what is called nominal dimensions and that actually such panels will be a few fractions of an inch smaller than. the indicated sizes in order to accommodate the thickness of the web 16 and to permit insertion-and removal of the panel 10. For example, the nominal-,2 x 4' size, which is most common, is in actuality 111%." X 311%".

By the term foil as used herein, applicant refers to metal foils which are of such a thickness as to be not self-supporting in the dimensions referred to above, such as the nominal 2, x 2 size or larger.

I claim:

1. An acoustical panel comprising a board of mineral fibers bound together by an hydrophilic binder, said board being of at least substantially 2' x 2' in dimension in the major plane thereof, a metal foil facing adhered to one face of said board throughout substantially the full extent of said face, acoustical openings extending through said foil and into said board to provide access to the interior of said board for sound energy impinging upon the ex posed face of said foil, and a moisture impervious membrane adhered to the opposite face of said board throughout substantially the full extent of said opposite face.

2. The panel of claim 1 in which said membrane is a metal foil.

3. The panel of claim 1 in which said metal foil is substantially smooth.

4. The panel of claim 3 in which said membrane is also a metal foil.

5. The panel of claim 1 in which said membrane is substantially free of acoustical openings therethrough.

6. The panel of claim 5 in which said metal foil is substantially smooth.

7. The panel of claim 6 in which said membrane is also a metal foil.

8. The panel of claim 2 in which said first mentioned foil is thicker than the foil of said opposite face.

9. A suspended acoustical ceiling of the lay-in type comprising a suspension grid having a plurality of parallel runners and a plurality of cross members extending between runners, said runners and cross members being an inverted T shape in cross section, a plurality of acoustical panels supported horizontally by said grid with the edges of said panels resting on the horizontal flanges of said runners and cross members, each of said panels being comprised of mineral fibers bound together by an hydrophilic binder to form a board, the dimension of each of said boards being at least substantially 2' x 2' in the plane ofthe ceiling, a metal foil facing adhered to one [face of said board throughout substantially the full extent ofsaid .face, acoustical openings extending through said foil and into said board to provide access to the interior of said board for sound energy impinging upon the exposed face of said foil, said panels being mounted in said suspension grid with their foilfacing downwardly toward the interior of the room, and a UNITED STATES PATENTS 2,028,272 1/ 1936 Burgess 52145 2,998,337 8/1961 Tillotson 52-145 X 3,074,505 1/1963 Schulz 52-144 X 3,122,216 2/1964 Boltz et a1. 52-622 X 3,246,063 4/1966 Podgurski 18133 FOREIGN PATENTS 990,491 4/ 1965 Great Britain.

ALFRED C. PERHAM, Examiner 

